Sagittal synostosis: I. Preoperative morphology of the skull

Abstract

The aim of this study was to characterise the preoperative morphology of the skull in sagittal synostosis in an objective and quantified way. The shapes of the skulls of 105 patients with isolated premature synostosis of the sagittal suture (SS group) were studied and compared with those of a control group of 72 children with unilateral incomplete cleft lip (UICL). A standardised radiocephalometric technique was used to obtain the images. A modification of a method developed by Kreiborg was used to analyse the radiocephalograms, which included the digitisation of 88 landmarks in the calvaria, skull base, and orbit (42 in the lateral and 46 in the frontal projections), the production of plots of mean shape for each group, and the intergroup comparison of a series of 81 variables (linear distance between selected landmarks, and angles defined by groups of three landmarks). Data from a subgroup of 66 patients aged 5 to 8 months were further compared to age-matched normative data in terms of seven angular and linear calvarial, cranial base and orbital variables. In a comparative analysis of the mean lateral plots, the foreheads of the study group (SS) had a more pronounced anterior slope and were also more convex. The vertex area was located more anteriorly, and was less convex. The occipital curvature was more prominent. Analysis of the mean frontal plots revealed a lack in convexity and lateral projection of the upper parietal regions, as well as a lower location of the line of maximum skull width. Comparison of the mean values of an SS subgroup to age-matched normative data showed a longer (p<0.001) and narrower skull (p<0.001) and a greater interorbital distance (p<0.001). The cranial base angle, the sella to nasion, and sella to basion lengths did not differ significantly. Sagittal synostosis is characterised by an extensive deformity of the cranial vault, with an essentially normal cranial base. The widened interorbital distance is probably related to compensatory metopic hyperactivity.

Computed Tomography–Based Morphometric Analysis of Extended Strip Craniectomy for Sagittal Synostosis

“…Interestingly, scaphocephalic patients were noted to have a similar anteroposterior position for the euryon as control subjects, which was approximately halfway along the length of skull. This was consistent with the findings of Guimaraes-Ferreira et al 21 and Kolar and colleagues, 24 who both noted a more inferior but unchanged anteroposterior location for the euryon in patients with sagittal synostosis as compared with control subjects.…”

Sagittal synostosis: II. Cranial morphology and growth after the modified pi-plasty

“…The vertex area was more anterior, lacked convexity, and there was a more prominent occipital curvature. The cranial base angle (n-sba) was smaller (more kyphotic) than that in the control (UICL 2m) group (see companion paper [24] for results of comparison to age-matched normative data and discussion of that issue). Analysis of the mean frontal plots showed a lack of convexity and lateral projection of the upper parietal regions, and a lower location of the line of maximum skull width.…”

“…Ell was assessed by a study of repeat tracing and digitisation of the full set of landmarks in 60 randomly selected cephalograms (30 in each projection) and was acceptable for every landmark (see companion paper for details [24]). …”

“…Non-white patients; those not of Scandinavian descent; and those with multiple suture synostosis, syndromic craniosynostosis, closure of the suture secondary to overshunting; and those who had had a previous craniofacial operation were excluded. The present sample was part of a larger group that included patients who were not operated on and was the basis for the companion paper [24].…”

“…The procedure for electronic recording of the landmarks was described in detail in the companion paper [24].…”